Analytic ultracentrifuge calibration and determination of lipoprotein-specific refractive increments
Accurate quantification of the major classes and subfractions of human serum lipoproteins is an important analytical need in the characterization and evaluation of therapy of lipid and lipoprotein abnormalities. For calibrating the analytic ultracentrifuge (AnUC), the authors routinely use a Beckman calibration wedge cell with parallel scribed lines 1 cm apart. Such a cell give a rectangular pattern in the schlieren diagram, which determines magnification and also provides an area corresponding to an invariant refractive increment. Complete calibration for AnUC analysis of lipoproteins also requires accurate determination of the specific refractive increments (SRI) of the major lipoprotein classes, namely low density lipoprotein (LDL) and high density lipoprotein (HDL). These are measured in the density in which they are analyzed, i.e., 1.061 g/ml for LDL and 1.200 g/ml for HDL. Five fresh serum samples were fractionated for total LDL and total HDL and their SRI determined. Total lipoprotein mass was determined using precise CHN elemental analysis and compositional analyses. The results yielded corrected SRI of 0.00142 and 0.00135 ..delta..n/g/100 ml for LDL and HDL. Thus, their current values using 0.00154 and 0.00149 ..delta..n/g/100 ml underestimate LDL and HDL by 9% and 11%. Corrections of all previous LDL and HDL AnUC data can be made using appropriate factors of 1.087 and 1.106.
- Research Organization:
- Lawrence Berkeley Lab., CA
- OSTI ID:
- 5009314
- Journal Information:
- Lipids; (United States), Vol. 19:7
- Country of Publication:
- United States
- Language:
- English
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